Kerry warns Russia against selling advanced missiles to Syria

ROME — Secretary of State John Kerry on Thursday cautioned Russia against selling advanced surface-to-air missiles to Syrian government forces, as U.S. officials warned that the delivery of the arms would threaten Israel and undercut efforts to reach a political agreement.

"We've made it crystal clear that we prefer that Russia would not supply them assistance," Kerry said during a news conference with Italy's new top diplomat. "That is on record. That has not changed."

Kerry declined to denounce the reported agreement between Russia and Syria's President Bashar al-Assad directly, but his warning to Russia was unmistakable.

The United States has long said that the proliferation of surface-to-air missiles "is potentially destabilizing with respect to the state of Israel," Kerry said. "We have made it very clear historically that that is a concern of the United States."

Russia has long supplied Assad's forces, but the potential sale of antiaircraft weapons reported Thursday by the Wall Street Journal threatens to undermine the agreement Kerry won in Moscow this week to press jointly for peace talks between Assad and his U.S.-backed opponents.

Moscow has previously sparred with Western governments over sales of helicopter and tank parts to the embattled regime. But the S-300 missiles, if delivered, would represent a huge leap in Syria's ability to defend itself from Israeli airstrikes as well as any future effort to impose a no-fly zone in support of Syria's rebels.

Considered one of the most potent air-defense systems currently in use, the S-300 system can track as many as 100 incoming aircraft or missiles at once, and engage up to a dozen, at long range.